Assessing the Preservation of Lumbar Lordotic Curvature in Everyday Sitting Conditions Assessed with an Inertial Measurement System

Background/Objectives: Lumbar lordotic curvature (LLC), closely associated with low back pain (LBP) when decreased, is infrequently assessed in clinical settings due to the spatiotemporal limitations of radiographic methods. To overcome these constraints, this study used an inertial measurement system to compare the magnitude and maintenance of LLC across various sitting conditions, categorized into three aspects: verbal instructions, chair type, and desk task types. Methods: Twenty-nine healthy participants were instructed to sit for 3 min with two wireless sensors placed on the 12th thoracic vertebra and the 2nd sacral vertebra. The lumbar lordotic angle (LLA) was measured using relative angles for the mediolateral axis and comparisons were made within each sitting category. Results: The maintenance of LLA (LLA(dev)) was significantly smaller when participants were instructed to sit upright (-3.7 +/- 3.9 degrees) compared to that of their habitual sitting posture (-1.2 +/- 2.4 degrees) (p = 0.001), while the magnitude of LLA (LLA(avg)) was significantly larger with an upright sitting posture (p = 0.001). LLA(dev) was significantly larger when using an office chair (-0.4 +/- 1.1 degrees) than when using a stool (-3.2 +/- 7.1 degrees) (p = 0.033), and LLA(avg) was also significantly larger with the office chair (p < 0.001). Among the desk tasks, LLA(avg) was largest during keyboard tasks (p < 0.001), followed by mouse and writing tasks; LLA(dev) showed a similar trend without statistical significance (keyboard, -1.2 +/- 3.0 degrees; mouse, -1.8 +/- 2.2 degrees; writing, -2.9 +/- 3.1 degrees) (p = 0.067). Conclusions: Our findings suggest that strategies including the use of an office chair and preference for computer work may help preserve LLC, whereas in the case of cueing, repetition may be necessary.